Human Trials Research Articles

Early Inflammation and Interferon Signaling Direct Enhanced Intestinal Crypt Regeneration after Proton FLASH Radiotherapy.

Ultra-high dose rate ("FLASH") radiotherapy (>40-60 Gy/s) is a promising new radiation modality currently in human clinical trials. Previous studies showed that FLASH proton radiotherapy (FR) improves toxicity of normal tissues compared to standard proton radiotherapy (SR) without compromising anti-tumor effects. Understanding this normal tissue sparing effect may offer insight into how toxicities from cancer therapy can be improved. Here, we show that compared to SR, FR resulted in improved acute weight recovery and survival in mice after whole-abdomen irradiation. Improved morbidity and mortality after FR were associated with greater proliferation of damage-induced epithelial progenitor cells followed by improved tissue regeneration. FR led to the accelerated differentiation of revival stem cells (revSCs), a rare damage-induced stem cell required for intestinal regeneration, and to qualitative and quantitative changes in activity of signaling pathways important for revSC differentiation and epithelial regeneration. Specifically, FR resulted in greater infiltration of macrophages producing TGF-β, a cytokine important for revSC induction, that was coupled to augmented TGF-β signaling in revSCs. In pericryptal fibroblasts, FR resulted in greater type I IFN (IFN-I) signaling, which directly stimulates production of FGF growth factors supporting revSC proliferation. Accordingly, the ability of FR to improve epithelial regeneration and morbidity was dependent on IFN-I signaling. In the context of SR, however, IFN-I had a detrimental effect and promoted toxicity. Thus, a tissue-level signaling network coordinated by differences in IFN-I signaling and involving stromal cells, immune cells, and revSCs underlies the ability of FLASH to improve normal tissue toxicity without compromising anti-tumor efficacy.

Novel Thermus thermophilus and Bacillus subtilis mixed-culture ferment extract provides potent skin benefits invitro and protects skin from aging.

Skin aging is one of the most abundant aging-related disorders that can be accelerated by excessive exposure to ultraviolet irradiation. Topically applied fermented skincare ingredients have gained mounting attentions due to their high concentration of various skin nourishing nutrients and bioactive components and low skin irritation potency. In the present study, we aim to fully demonstrate the skin-related benefits of a novel extract of Thermus thermophilus and Bacillus subtilis mixed-culture ferment (TBFE). TBFE was prepared through an innovative mixed-culture fermentation process. The contents of nutrients and bioactive ingredients were quantified by different methods accordingly. Both invitro tests and randomized controlled human trial were utilized to further demonstrate multifaceted beneficial effects on human skin, as well as the potential mechanisms. Our results showed that TBFE upregulated the expression of type IV collagen, elastin, aquaporin-3, and dermal-epidermal junction markers, while inhibited production of melanin, in different skin cell models. Moreover, TBFE inhibited the generation of reactive oxygen species and pro-inflammatory mediators induced by ultraviolet irradiation in normal human keratinocytes, while stimulated autophagy in senescent keratinocytes. Results from clinical studies confirmed those invitro findings, demonstrating that TBFE at 5% and 20% concentration provides anti-aging properties in subjects with sensitive skin, in terms of improving wrinkles, moisturization, and skin lightening. In summary, we demonstrate that a novel mixed-culture ferment extract has promising anti-aging effects, which may be attributed to anti-oxidation, anti-inflammation, and promotion of autophagy in skin cells.

Unlocking the Insightful Antidiabetic Effects of Lemongrass (Cymbopogon citratus): A Comprehensive Review

Lemongrass (Cymbopogon citratus) has emerged as a noteworthy contender in traditional medicine for its aromatic and therapeutic attributes, yet its potential as an antidiabetic agent remains largely unexplored in the literature. To address this gap, this study endeavors to provide a comprehensive overview of lemongrass role in diabetes management and the underlying pathways involved. Rich in bioactive compounds such as citral, flavonoids, and essential oils, lemongrass boasts a diverse array of medicinal properties. Research indicates its capability to modulate blood glucose levels, improve insulin sensitivity, and fortify pancreatic β-cell function primarily through antioxidant and anti-inflammatory mechanisms. Animal studies have demonstrated substantial reductions in fasting blood glucose and enhanced glucose tolerance, ascribed to heightened insulin signaling and inhibition of carbohydrate metabolism enzymes. Additionally, lemongrass exhibits a positive impact on lipid profiles, thereby mitigating cardiovascular risks associated with diabetes. Limited human trials have corroborated these findings, showcasing improvements in glycemic control and lipid metabolism following lemongrass consumption. In conclusion, lemongrass emerges as a promising adjunctive therapy for diabetes management, owing to its natural composition and multifaceted mechanisms. Nonetheless, further investigation, particularly through rigorous clinical trials, is imperative to determine optimal dosages, long-term safety, and efficacy, thereby facilitating its seamless integration into conventional diabetes treatment protocols.

Rheological characterization and print quality studies of gelatin/collagen I/PEGDA hydrogels

Bioprinting is an up-and-coming technology that uses the basis of additive manufacturing and applies it to the field of tissue engineering. Bioprinting is used to create 3D models of diseased tissue and organs, test cellular responses to drug therapies, and create potentially transplantable organs and vasculature. Bioprinting has gained increasing interest especially in drug discovery, as the traditional 2D cell culture models have been shown to produce results that are not mimicked in animal and human trials. Bioprinters use materials called bioinks, developed from hydrogels which can contain cells and biological factors. While there are commonly used bioinks, there is a need for the development of a diverse range of bioinks for varying applications. In this study, an alternative bioink was developed. The formulations included gelatin, collagen I, and varying amounts of poly (ethylene glycol) diacrylate (PEGDA). These formulations were subject to rheological characterization and print quality analysis. Formulations with higher concentrations of PEGDA had higher degrees of shear-thinning, higher viscosity recovery, lower viscosities, and less dominant gel behavior. The print quality studies showed that the formulations with lower concentrations of PEGDA had better printability, print accuracy, and print fidelity. Formulation P5 had the best overall print quality.

The Comparison of Immunomodulatory Properties of Canine and Human Wharton Jelly-Derived Mesenchymal Stromal Cells.

Although therapies based on mesenchymal stromal cells (MSCs) are being implemented in clinical settings, many aspects regarding these procedures require further optimization. Domestic dogs suffer from numerous immune-mediated diseases similar to those found in humans. This study aimed to assess the immunomodulatory activity of canine (c) Wharton jelly (WJ)-derived MSCs and refer them to human (h) MSCs isolated from the same tissue. Canine MSC(WJ)s appeared to be more prone to in vitro aging than their human counterparts. Both canine and human MSC(WJ)s significantly inhibited the activation as well as proliferation of CD4+ and CD8+ T cells. The treatment with IFNγ significantly upregulated indoleamine-2,3-dioxygenase 1 (IDO1) synthesis in human and canine MSC(WJ)s, and the addition of poly(I:C), TLR3 ligand, synergized this effect in cells from both species. Unstimulated human and canine MSC(WJ)s released TGFβ at the same level (p > 0.05). IFNγ significantly increased the secretion of TGFβ in cells from both species (p < 0.05); however, this response was significantly stronger in human cells than in canine cells. Although the properties of canine and human MSC(WJ)s differ in detail, cells from both species inhibit the proliferation of activated T cells to a very similar degree and respond to pro-inflammatory stimulation by enhancing their anti-inflammatory activity. These results suggest that testing MSC transplantation in naturally occurring immune-mediated diseases in dogs may have high translational value for human clinical trials.

Targeting Super-Enhancer-Driven Transcriptional Dependencies Suppresses Aberrant Hedgehog Pathway Activation and Overcomes Smoothened Inhibitor Resistance.

Aberrant activation of the Hedgehog (Hh) signaling pathway plays important roles in oncogenesis and therapeutic resistance in several types of cancer. The clinical application of FDA-approved Hh-targeted smoothened inhibitors (SMOi) is hindered by the emergence of primary or acquired drug resistance. Epigenetic and transcriptional-targeted therapies represent a promising direction for developing improved anti-Hh therapies. In this study, we integrated epigenetic/transcriptional-targeted small-molecule library screening with CRISPR/Cas9 knockout library screening and identified CDK9 and CDK12, two transcription elongation regulators, as therapeutic targets for antagonizing aberrant Hh activation and overcoming SMOi resistance. Inhibition of CDK9 or CDK12 potently suppressed Hh signaling and tumor growth in various SMOi responsive or resistant Hh-driven tumor models. Systemic epigenomic profiling elucidated the Hh-driven super-enhancer (SE) landscape and identified IRS1, encoding a critical component and cytoplasmic adaptor protein of the insulin-like growth factor (IGF) pathway, as an oncogenic Hh-driven SE target gene and effective therapeutic target in Hh-driven tumor models. Collectively, this study identifies SE-driven transcriptional dependencies that represent promising therapeutic vulnerabilities for suppressing the Hh pathway and overcoming SMOi resistance. As CDK9 and IRS inhibitors have already entered human clinical trials for cancer treatment, these findings provide comprehensive preclinical support for developing trials for Hh-driven cancers. Significance: Dissecting transcriptional dependencies driven by super-enhancers uncovers therapeutic targets in Hedgehog-driven cancers and identifies strategies for overcoming resistance to smoothened inhibitors.

Evaluating the Healing Properties of Quercetin-Enhanced Nanoparticle Ointments in Diabetic Rats

Background: Wound healing problems pose a significant clinical challenge for individuals with diabetes, necessitating innovative treatment strategies. Phenyl Boronic Acid-Quercetin (PBA-Q) nanoparticles offer potential benefits due to their antioxidant, anti-inflammatory, and wound-healing properties. Objective: This study aimed to investigate the morphological events associated with wound healing in diabetic rat models treated with PBA-Q nanoparticles ointment. Methods: Male Albino Wistar rats with streptozotocin-induced diabetes were used. Diabetes was confirmed with blood glucose levels exceeding 250 mg/dL. Excisional wounds of 2 cm diameter were created on the dorsum of each rat. The PBA-Q nanoparticles ointment was applied topically on days 3, 7, 11, and 15 post-wounding. Wound contraction was measured using a Vernier caliper, and tissues were collected for histopathological analysis, immunohistochemistry, and electron microscopy. Statistical analysis was performed using SPSS version 25.0. Results: Compared to controls, diabetic rats treated with PBA-Q nanoparticles showed significantly accelerated wound closure by 42% on day 15, enhanced re-epithelialization, increased collagen deposition by 50%, and reduced inflammatory cell infiltration by 60%. Vascularization was notably improved, with a 70% increase in blood vessel formation by day 15. Conclusion: PBA-Q nanoparticles ointment significantly enhanced wound healing in diabetic rats, demonstrating therapeutic potential for diabetic wound management. Further research is needed to validate these findings in human clinical trials.

A comprehensive review of the characterization, host interactions, and stabilization advancements on probiotics: Addressing the challenges in functional food diversification.

The demand for functional food is rising in tandem with the prevalence of chronic diseases. Probiotics play a crucial role in functional food development, yet their ability to confer health benefits to the host remains a topic of debate according to Food and Agriculture Organization/World Health Organization requirements. The application of culturomics, innovative isolation techniques, within the realm of probiotics is increasingly deemed essential for fully harnessing the latent potential of microbial reservoirs. Nevertheless, its application remains confined predominantly to human fecal sources. Following the integration of probiogenomics, significant advancements have been made in the safety assessment of probiotics. However, the adoption of novel probiotic microorganisms has yet to match the requisite pace. Progress in research concerning host-probiotic interactions by employing omics technologies, particularly in animal models, is notable. Nonetheless, the comprehensive elucidation of mechanisms of action and human trial studies are lagging behind. Additionally, the viability of probiotics, spanning from their production as functional foods to their transit to the human colon, has markedly improved through encapsulation techniques. Nevertheless, opportunities for exploration persist regarding alternative coating materials and diverse encapsulation methodologies. Furthermore, there is a discernible transition in the domain of probiotic-based functional foods, shifting away from a primarily dairy-centric focus toward inclusion in a broader array of food categories. This comprehensive review addresses critical issues ranging from isolation sources and novel techniques to the final functional food developments. while doing so, it explores probiogenomics applications for probiotic characterization, investigations into host-probiotic interactions, and strategies for probiotic stabilization under harsh environmental conditions.

Production of Bioactive Peptides from Microalgae and Their Biological Properties Related to Cardiovascular Disease

Microalgae are a substantial group of unicellular prokaryotic and eukaryotic marine organisms. Due to their high protein content of 50–70%, microalgae have the potential to become a sustainable alternative protein source, as well as aiding in the development of bioactive peptide-based nutraceuticals. A series of major steps are involved in the production of peptides from microalgae, which include the disruption of the microalgal cell wall, the hydrolysis of proteins, and the extraction or isolation of peptides derived from hydrolysis. Physical methods of cell wall disruptions are favored due to the ability to obtain high-quality protein fractions for peptide production. Bioactive peptides are protein fragments of two to twenty amino acid residues that have a beneficial impact on the physiological functions or conditions of human health. Strong scientific evidence exists for the in vitro antioxidant, antihypertensive, and anti-atherosclerotic properties of microalgal peptides. This review is aimed at summarizing the methods of producing microalgal peptides, and their role and mechanisms in improving cardiovascular health. The review reveals that the validation of the physiological benefits of the microalgal peptides in relation to cardiovascular disease, using human clinical trials, is required.

A review of the therapeutic effects of polyphenols on non-alcoholic fatty liver disease: Focus on oxidative stress

A substantial body of research suggests that polyphenols may have health benefits, particularly in metabolic disorders associated with obesity, such as non-alcoholic fatty liver (NAFLD), type 2 diabetes, and cardiovascular disease. Given the importance of oxidative stress in the pathogenesis of metabolic disorders, significant emphasis has recently been placed on the characteristics of polyphenols in obesity-related problems. This narrative review summarizes the current knowledge on the inhibitory effects of polyphenols, including curcumin, resveratrol, baicalin, nobiletin, and quercetin, on oxidative stress, with a focus on the role of the Nrf2 pathway. This review compiles the data from articles showing that the aforementioned polyphenols improve health in metabolic diseases by regulating Nrf2 and its target proteins involved in reducing oxidative stress. However, due to the limitations of in vitro and in vivo investigations, as well as the lack of long-term human clinical trial studies, further high-quality research is required to definitively demonstrate the clinical usefulness of polyphenols for the prevention and management of NAFLD.

(Invited) Skin-Interfaced Wearable Sweat Biosensors

The rising research interest in personalized medicine promises to revolutionize traditional medical practices. This presents a tremendous opportunity for developing wearable devices toward predictive analytics and treatment. In this talk, I will introduce our efforts in developing wearable biosensors for non-invasive molecular analysis. Such wearables can autonomously access body fluids (e.g., human sweat) across the activities and continuously measure a broad spectrum of analytes including metabolites, nutrients, hormones, proteins, and drugs. I will highlight our recent works in the design of wearable and wireless devices for the real-time electrochemical detection of picomolar-level proteins (i.e., inflammatory biomarker C-reactive) and hormones (i.e., estradiol) in sweat. Laser engraving, inkjet printing, and direct-ink-writing 3D printing are used to manufacture high-performance nanomaterials-based biosensors at large scale and low cost. The clinical value of our wearable systems is evaluated through various human trials toward precision nutrition, stress/mental health assessment, chronic disease management, and drug personalization. I will also discuss our research progress on energy harvesting from the human body and the environment to realize battery-free wireless wearable sensing. These wearable technologies could open the door to a wide range of personalized monitoring, diagnostic, and therapeutic applications.

Predicting Clinical Outcomes of SARS-CoV-2 Drug Efficacy with a High-Throughput Human Airway Microphysiological System.

The average cost to bring a new drug from its initial discovery to a patient's bedside is estimated to surpass $2 billion and requires over a decade of research and development. There is a need for new drug screening technologies that can parse drug candidates with increased likelihood of clinical utility early in development in order to increase the cost-effectiveness of this pipeline. For example, during the COVID-19 pandemic, resources were rapidly mobilized to identify effective therapeutic treatments but many lead antiviral compounds failed to demonstrate efficacy when progressed to human trials. To address the lack of predictive preclinical drug screening tools, PREDICT96-ALI, a high-throughput (n = 96) microphysiological system (MPS) that recapitulates primary human tracheobronchial tissue,is adapted for the evaluation of differential antiviral efficacy of native SARS-CoV-2 variants of concern. Here, PREDICT96-ALI resolves both the differential viral kinetics between variants and the efficacy of antiviral compounds over a range of drug doses. PREDICT96-ALI is able to distinguish clinically efficacious antiviral therapies like remdesivir and nirmatrelvir from promising lead compounds that do not show clinical efficacy. Importantly, results from this proof-of-concept study track with known clinical outcomes, demonstrate the feasibility of this technology as a prognostic drug discovery tool.

Unveiling the Immunostimulatory Potential of Rhus Toxicodendron in Immunocompromised Balb/C Mice Induced with Cyclophosphamide.

This study investigated how Rhus toxicodendron (RT) (6C, 30C, and 200C) can boost the immune system of BALB/c mice that were given cyclophosphamide (CPM), which is an anticancer drug that weakens the immune system. RT, known for its historical use in traditional homeopathic remedies, has demonstrated immunomodulatory and anti-inflammatory effects in various experimental models. To test the immune-boosting effects of RT, CPM (80 mg/kg) was given intraperitoneally to mice on days 4, 8, and 12 of the study but not to the normal control group. CPM-induced immunosuppression led to significant decreases in red blood cell (RBC), white blood cell (WBC), and hemoglobin (Hb) levels, and reduced spleen and thymus indices. Phagocytic activity, cytokine concentrations, and spleen architecture were also adversely affected. RT treatment, particularly at 200C, significantly ameliorated these effects, improving RBC, WBC, and Hb levels. Furthermore, RT partially prevented CPM-induced atrophy of immune organs. Treatment positively influenced cytokine production at both the protein and mRNA levels, restoring immune balance. Histopathological results confirmed that RT stimulated the immune system. The cells were more stable, and the white pulp in the spleen was arranged in a regular pattern. These findings suggest that RT may serve as an adjunctive immunostimulant therapy for conditions characterized by immunosuppression. However, further investigations in other immunocompromised states must validate these results before considering human clinical trials.

Combinatorial effect of Apigenin-resveratrol on white adipocyte plasticity and trans-differentiation for activating lipid metabolism.

Inducing browning in white adipocytes has emerged as a promising therapeutic approach for addressing obesity. Bioactive that modulate the WAT microenvironment to induce trans browning in white adipocytes have been explored as a strategy to control unregulated lipid storage. However, relying on a single bioactive for modulating lipid metabolism has proven insufficient in obese individuals during human trials, because these compounds primarily activate a single biochemical pathway in promoting browning. Consequently, there is a growing emphasis on targeting multiple pathways to ensure a safe and effective browning process. The present study investigated the combinatorial effect of bioactives namely Apigenin and Resveratrol for activating multiple pathways for effective trans-browning of white adipocytes. The combination was seen to promote the browning more effectively than the single bioactive, as the combination simultaneously activated multiple signaling pathways to induce angiogenesis-mediated browning in primary white adipocytes isolated from obese mice. Activation of PI3K signaling via estrogen receptor-α-dependent pathway resulted in simultaneous activation of angiogenesis and trans browning in white adipocytes. The study provides valuable insights into the potential use of bioactives in combination with therapeutic intervention to improve the overall health of obese subjects by enhancing lipid metabolism by activating trans-differentiation of white adipocytes.

Anti-LAG-3 boosts CD8 T cell effector function

LAG-3 is the third immune checkpoint pathway successfully targeted for cancer therapy. Although ineffective as a monotherapy, combination of LAG-3 and PD-1 blockade improves survival from advanced melanoma. In this issue of Cell, two studies in mice and a human clinical trial provide insights on LAG-3 in immune regulation.

Tau-Targeted Immunotherapy for Alzheimer's Disease: Insight into Clinical Trials

The use of immunotherapy as a therapeutic approach to Alzheimer's Disease (AD) is gaining rapid interest, with the primary goal of targeting abnormalities that impact neuronal viability through specific antibodies. Currently, clinical strategies focus intensively on targeting the two main pathologies associated with AD, beta-amyloid (Ab) and tau. This review examines ongoing research in the realm of tau immunotherapy, including clinical trials that demonstrate promising potential for halting AD progression. Several trials are underway, focusing on improving tau-targeted immunotherapy tools based on passive and active immunization protocols. Tau-targeted therapies have proven relevant and demonstrated safety and efficacy in both animal models and human clinical trials. Some studies have demonstrated a reduction in tau protein aggregation in animal models, highlighting a potential mechanism by which these antibodies inhibit the spread of tau protein in the extracellular space. Recent discoveries have highlighted the potential role of tau-targeting therapy with antibodies and have revealed significant promise in treating pathological tau in AD.

Efficacy of ivermectin and its metabolites against Plasmodium falciparum liver stages in primary human hepatocytes.

Ivermectin, a broad-spectrum anti-parasitic drug, has been proposed as a novel vector control tool to reduce malaria transmission by mass drug administration. Ivermectin and some metabolites have mosquito-lethal effect, reducing Anopheles mosquito survival. Ivermectin inhibits liver stage development in a rodent malaria model, but no inhibition was observed in a primate malaria model or in a human malaria challenge trial. In the liver, cytochrome P450 3A4 and 3A5 enzymes metabolize ivermectin, which may impact drug efficacy. Thus, understanding ivermectin metabolism and assessing this impact on Plasmodium liver stage development is critical. Using primary human hepatocytes (PHHs), we characterized ivermectin metabolism and evaluated the efficacy of ivermectin and its primary metabolites M1 (3″-O-demethyl ivermectin) and M3 (4-hydroxymethyl ivermectin) against Plasmodium falciparum liver stages. Two different modes of ivermectin exposure were evaluated: prophylactic mode (days 0-3 post-infection) and curative mode (days 3-5 post-infection). We used two different PHH donors and modes to determine the inhibitory concentration (IC50) of ivermectin, M1, M3, and the known anti-malarial drug pyrimethamine, with IC50 values ranging from 1.391 to 14.44, 9.95-23.71, 4.767-8.384, and 0.9073-5.416 µM, respectively. In our PHH model, ivermectin and metabolites M1 and M3 demonstrated inhibitory activity against P. falciparum liver stages in curative treatment mode (days 3-5) and marginal activity in prophylactic treatment mode (days 0-3). Ivermectin had improved efficacy when co-administered with ketoconazole, a specific inhibitor of cytochrome P450 3A4 enzyme. Further studies should be performed to examine ivermectin liver stage efficacy when co-administered with CYP3A4 inhibitors and anti-malarial drugs to understand the pharmacokinetic and pharmacodynamic drug-drug interactions that enhance efficacy against human malaria parasites in vitro.

HDAC3 genetic and pharmacologic inhibition radiosensitizes fusion positive rhabdomyosarcoma by promoting DNA double-strand breaks

Radiotherapy (RT) plays a critical role in the management of rhabdomyosarcoma (RMS), the prevalent soft tissue sarcoma in childhood. The high risk PAX3-FOXO1 fusion-positive subtype (FP-RMS) is often resistant to RT. We have recently demonstrated that inhibition of class-I histone deacetylases (HDACs) radiosensitizes FP-RMS both in vitro and in vivo. However, HDAC inhibitors exhibited limited success on solid tumors in human clinical trials, at least in part due to the presence of off-target effects. Hence, identifying specific HDAC isoforms that can be targeted to radiosensitize FP-RMS is imperative. We, here, found that only HDAC3 silencing, among all class-I HDACs screened by siRNA, radiosensitizes FP-RMS cells by inhibiting colony formation. Thus, we dissected the effects of HDAC3 depletion using CRISPR/Cas9-dependent HDAC3 knock-out (KO) in FP-RMS cells, which resulted in Endoplasmatic Reticulum Stress activation, ERK inactivation, PARP1- and caspase-dependent apoptosis and reduced stemness when combined with irradiation compared to single treatments. HDAC3 loss-of-function increased DNA damage in irradiated cells augmenting H2AX phosphorylation and DNA double-strand breaks (DSBs) and counteracting irradiation-dependent activation of ATM and DNA-Pkcs as well as Rad51 protein induction. Moreover, HDAC3 depletion hampers FP-RMS tumor growth in vivo and maximally inhibits the growth of irradiated tumors compared to single approaches. We, then, developed a new HDAC3 inhibitor, MC4448, which showed specific cell anti-tumor effects and mirrors the radiosensitizing effects of HDAC3 depletion in vitro synergizing with ERKs inhibition. Overall, our findings dissect the pro-survival role of HDAC3 in FP-RMS and suggest HDAC3 genetic or pharmacologic inhibition as a new promising strategy to overcome radioresistance in this tumor.

Omega-3 Fatty Acids and Arrhythmias.

The pro- and antiarrhythmic effects of omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been extensively studied in preclinical and human trials. Despite early evidence of an antiarrhythmic role of n-3 PUFA in the prevention of sudden cardiac death and postoperative and persistent atrial fibrillation (AF), subsequent well-designed randomized trials have largely not shown an antiarrhythmic benefit. Two trials that tested moderate and high-dose n-3 PUFA demonstrated a reduction in sudden cardiac death, but these findings have not been widely replicated, and the potential of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) to reduce arrhythmic death in combination, or as monotherapy, remains uncertain. The accumulated clinical evidence does not support supplementation of n-3 PUFA for postoperative AF or secondary prevention of AF. Several large, contemporary, randomized controlled trials of high-dose n-3 PUFA for primary or secondary cardiovascular prevention have demonstrated a small, significant, dose-dependent increased risk of incident AF compared with mineral oil or corn oil comparator. These findings were reproduced with both icosapent ethyl monotherapy and a mixed EPA+DHA formulation. The proarrhythmic mechanism of increased AF in contemporary cohorts exposed to high-dose n-3 PUFA is unknown. EPA and DHA and their metabolites have pleiotropic cardiometabolic and pro- and antiarrhythmic effects, including modification of the lipid raft microenvironment; alteration of cell membrane structure and fluidity; modulation of sodium, potassium, and calcium currents; and regulation of gene transcription, cell proliferation, and inflammation. Further characterization of the complex association between EPA, EPA+DHA, and DHA and AF is needed. Which formulations, dose ranges, and patient subgroups are at highest risk, remain unclear.

Tutorial on Firth's Logistic Regression Models for Biomarkers in Preclinical Space.

Preclinical studies are broad and can encompass cellular research, animal trials, and small human trials. Preclinical studies tend to be exploratory and have smaller datasets that often consist of biomarker data. Logistic regression is typically the model of choice for modeling a binary outcome with explanatory variables such as genetic, imaging, and clinical data. Small preclinical studies can have challenging data that may include a complete separation or quasi-complete separation issue that will result in logistic regression inflated coefficient estimates and standard errors. Penalized regression approaches such as Firth's logistic regression are a solution to reduce the bias in the estimates. In this tutorial, a number of examples with separation (complete or quasi-complete) are illustrated and the results from both logistic regression and Firth's logistic regression are compared to demonstrate the inflated estimates from the standard logistic regression model and bias-reduction of the estimates from the penalized Firth's approach. R code and datasets are provided in the supplement.